MX2013008941A - Method for manufacturing antimicrobial acrylic materials. - Google Patents

Abstract

Acrylic materials with antimicrobial activity are tumble blended, melted and extruded through an extruder. The resulting polymer compounds include an acrylic resin, such as methylmethacrylate polymers, copolymers and multipolymers, and blends thereof, silver-containing antimicrobial additives; and optional additives such as impact modifiers, flow promoters, stabilizers and coloring agents. The properties of the acrylic materials, especially the antimicrobial performance, are strongly dependent on the manufacturing process conditions, including feed resins pre-drying, residual moisture content, screw speed and melt temperature. The materials composition and manufacturing procedures are equally significant.

Description

METHOD FOR MANUFACTURING ANTIMICROBIAL ACRYLIC MATERIALS Field of the Invention There is disclosed herein a process for making acrylic compounds such as sheets, films, rods, tubes and other extruded profiles and / or downstream articles, which exhibit antimicrobial activity. The process uses compositions based on acrylic resins, both standard and modified on impact, including multi-polymer resins and polymer blends, with silver-containing antimicrobial additives and optional components such as flow promoters, stabilizers, dyes, etc. More specifically, processing conditions are described to improve the antimicrobial performance and improve! the optical performance. Antimicrobial resins, and. , downstream items can find a ety of uses, including medical and consumer applications.

Background of the Invention Acrylic is widely used in consumer and medical applications. The acrylic polymer provides. a durable transparent or translucent product characteristic with desirable appearance, substantial abrasion resistance, chemical resistance and colorability. Acrylic materials are incorporated in showers, tubs: bath, whirlpool, bath and floor and panels Ref. 242551 of kitchen used in homes, hotels, hospitals, restaurants or other residential or commercial environments. These acrylic-based products are under constant exposure to the bacteria, fungi and microbes that exist in their respective environments and there is a wide range of consumer and medical products that require antimicrobial performance.

In the medical industry, the use of plastics is continuously increasing. A high degree of post-operative infections in hospitals, estimated as being 5-10% of patients in the hospital in the United States, prolongs hospital stay of infected patients by an average of 4-5 days and increases the 'cost of hospitalization. In this way the medical industry is challenged to develop plastic materials with ". good antimicrobial performance.

The antimicrobial technology for polymers is typically based on additives, either organic or inorganic. Representative organic additives are organic ingredients based on alcohol, chlorine, and ammonium which have found wide use since a pair of patents of 1964, written for the antimicrobial agents tricotan and brominated salicylanilides. More recently, attempts have been made to incorporate organic additives into polymeric substrates. Patent Publication WO 2000/014128 describes acrylic polymers having antimicrobial characteristics through the incorporation of antimicrobial agents that exhibit controlled migration through the acrylic polymer until an equilibrium point is obtained. US Patent 7,579,389 discloses that although inorganic antimicrobial agents, such as silver and copper, tend to discolor thermoformed articles, organic additives such as isothiazoline, an oxathiazine, an azole, and mixtures thereof can be combined with a acrylic precursor solution. However, the low thermal stability and the toxicity of the degradation products make their materials less suitable for the medical industry.

The U. A. Patents Nos. 6,146,688 and 6,572,926 describe a polymer technology for an organic antimicrobial additive sold under the trademark BIOSAFE (Biosafe, Inc., Pittsburgh, PA). The invention evolved as a method for imparting antimicrobial properties to polymeric substrates based on the addition of quaternary ammonium salts. This technology provides a permanent antimicrobial activity despite the fact that it eliminates common problems such as discoloration, opacity and worries about migration out of plastic, however, due to the environment with a high bacterial concentration for medical devices. They are necessary further improvements in efficiency performance (annihilation index).

Representative inorganic antimicrobial products are based on the oligodynamic effect of metal ions, such as aluminum, copper, iron, zinc and especially silver. The silver-based antimicrobial technology is highly effective and has been used in the management of wounds and as additives in coatings since the 60's. 'Silver antimicrobials for plastics were introduced in the 90' s and today are widely used in materials for medical devices and applications of public devices. A conventional method for obtaining antimicrobial medical devices is the deposition of metallic silver directly on the surface of the substrate, for example, through vapor-coating, spray coating, ion-ray coating, deposition or electro-deposition of silver from the solution. The Patent of E. ÜJ? . No. 6,162,533 discloses a transparent base sheet coated with an acrylate coating layer cured with radiation that includes various antimicrobial agents such as the inorganic antimicrobial agent a! base! of silver carried in zirconium or calcium phosphate, silica gel, glass powder, and other carriers. The techniques; of coating suffer disadvantages, such as poor adhesion, lack of uniformity in the coating, secondary processing and the need for special processing conditions. Also, it is difficult to properly hide the layer or the. wrapped areas.

In recent years, attempts have been made to form inorganic antimicrobial additive compounds in different polymers. The above examples described in E.U.A. 5, 244, 667 use a large surface area of porous silica gel covered with an antimicrobial layer of aluminosilicate. Examples are given with various classes of polymers, including PVC (polyvinyl chloride), polypropylene, HDPE (high density polyethylene) and polystyrene. A recognized disadvantage is the discoloration seen with the compositions when they are molded under heating. The patent of E. U. A. No. 5, 827, 524 claims to have solved this problem by describing antimicrobial compositions of dioxide; crystalline sil-icón with an improved color stability and a good antimicrobial activity that contains silver ions and one or two optional metal ions from the zinc and copper group. Still, the support data falls short in demonstrating the high standard of color stability required for the grades of optical material. A broad spectrum of thermoplastic polymers and thermosetting are listed including acrylic resins. The Patent of E. U :. A:.: No. 7,541,418 describes a compound molded with polycarbonate A thermoplastic containing an antimicrobial compound, AgaM b 22 (P04) 3, wherein M 1 is at least one ion selected from the group consisting of alkali metal ions, alkaline earth metal ions, an ammonium ion and a hydrogen ion. M2 is a tetravalent metal selected from the group of Ti, Zr and Sn. Patents of E. U. A. Nos. 6, 939, 820 and 7,329,301 also describe antimicrobial silver additives for such purposes. Each of the United States Patent Numbers 7,579,389; 7,541, 418; 5,827,524; 6,593,260, 6,939,820 and 7,329,301 are incorporated by reference herein in their entirety.

An object is to provide a simple and cost-effective method for producing antimicrobial acrylic materials without the aforementioned drawbacks.

Brief Description of the Invention The present disclosure provides a method for producing antimicrobial acrylic materials under controlled process conditions with surprisingly improved efficiency and optical performance. ·· |: More specifically, the description relates to processing conditions such as melt mixing eqent, spindle configuration, residence time, spindle speed, melting temperature range and moisture content of the melted group to optimize antimicrobial performance and optical performance.

The antimicrobial formulations described herein are broadly based on a range of acrylics including PMMA, MA copolymer and multipolymers, impact-modified acrylic compounds and their alloys. The antimicrobial technology is based on a variety of commercially available silver-based additives, for example, Bactiglas, NanoSilver, Ionpure, Zeolite, SelectSilver, AlphaSan, etc. The content of the antimicrobial additive is in the range of about 0.1% by weight to about 10% ert of the entire composition.

Brief Description of the Figures Figure 1 graphically illustrates the effect of, the loading of the additive on the degree of release of the plate.

Figure 2 graphically illustrates the effects of barrel temperature and spindle speed on: the degree of release. : Figure 3 graphically illustrates the effect of: the barrel temperature on the optical properties of: an injection molded material.

Detailed description of the invention In a first aspect, the present disclosure involves a method for producing antimicrobial acrylic materials by melt blending of polymers, process aids and low antimicrobial additives. d Controlled process conditions with optimal antimicrobial and optical performance. The acrylic materials produced have antimicrobial characteristics that inhibit bacterial, fungal, microbial and other pathogen or non-pathogen growth.

The antimicrobial formulations are based on a range of acrylic compounds including copolymers and multipolymers PMMA (poly (methyl methacrylate)), MMA (methyl methacrylate), impact-modified acrylic compounds and their alloys. The resin components used in the invention contain additives, including resins and compositions that impart impact resistance, such as polymers with a low Tg and copolymers of aliphatic esters of acrylic acid, polymers and copolymers of 1,3-butadiene, styrene / butadiene, styrene / isoprene. ' and styrene / ethylene-butylene copolymers, rubbers; from;;; EPDM (ethylene propylene diene monomer), polyisobutyl ether, polyurethane and silicone gums.

Antimicrobial products are used: in applications that include but are not limited to medical devices and accessories, where typical examples are regulating valves, luer connectors, filter housings, nails, Y-sites, measuring cups, etc., and consumer applications such as vacuum cleaners, paper towel dispensers, manual dryers, potato-tubs, showers, floor for bathrooms and kitchens, etc. Manufacturing methods include but are not limited to, extrusion molding and composites, extruded sheets, and their thermoformed and fabricated articles, acrylic films. and foam products and extruded profiles.

Acrylic can be prepared by various methods including volume polymerization, solution, emulsion, suspension and granulation. This polymer can also be obtained in a liquid monomer from fully polymerized beads, sheets, panels or rods. After the acrylic polymer is prepared, the acrylic polymer can be processed by casting, pouring, sheet thermoforming, extruding, calendering, coating, brushing, spraying and machining with conventional tools to form a desired end product. -;, The acrylic polymers could also impact the modified PMMA and impact the modified acrylic multipolymers. Examples of the leather reinforcing portion of such systems include such polybutadienes, copolymers of poly (styrene / butadienes), poly (methyl methacrylate / butadienes), polyisoprenes, polyisobutylenes, poly (isobutylene / isoprene) copolymers, poly (acrylonitrile / butadienes) , polyacrylates, polyurethanes, neoprene, silicone rubbers, chlorosulfonated polyethylene,:. gums ethylene-propylene, and other rubbery materials, gums, polyethylene chlorosulfate, ethylene-propylene gums, and other leathery materials.

Intake into the above gums may be the monomers detailed below for the resin phase. The monomers to be grafted must be compatible with the particular monomers used in the resin phase for a particular composition. Preferably, the same monomers are used in both. By "compatible" it means polymers that show a strong affinity to each other: such that they can disperse one into the other in small domain sizes. The smaller the domain sizes, the more compatible the polymers are. A further explanation of the compatibility can be found in Advances in Chemistry Series, No. 99, "Multi-Component Polymer Systems", edited by R. · F. Gould, 1971, incorporated herein by reference.

The resin phase is any polymer or copolymer that is compatible with the grafted rubber phase. Examples of suitable monomers include: acrylates, methacrylates, nitriles, styrenes, vinyl / ethers, yinyl halides and other monovinyl compounds and the like.; Particularly suitable monomers include methacrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, acrylonitrile, methacrylonitrile, styrene, alpha-methylstyrene, butyl vinyl ether and vinyl chloride.

Preferably, for this invention, the gum phase is polybutadiene grafted with ethyl methacrylate, styrene, and optionally methylacrylate, ethylacrylate; or acrylonitrile.

Preferably, the resin phase is a terpolymer of methyl methacrylate, styrene, and optionally methylacrylate, ethylacrylate, or acrylonitrile.

More preferably, the molding compositions are prepared from a grafted polybutadiene phase and a polymeric resin phase wherein the polybutadiene fraction of the grafted polybutadiene phase is calculated as being: from 5 to 25% by weight of the composition of total molding. The polymeric resin phase contains from about 60 to 80 parts of methyl methacrylate, from 15 to 30 parts of styrene: yd: e:: 0 to 15 parts of methylacrylate, ethylacrylate or acrylonitrile i The grafted polybutadiene is polybutadiene grafted with: methyl methacrylate, styrene and optionally either methylacrylate, ethylacrylate or acrylonitrile wherein the overall ratio of polybutadiene to the grafted monomers is in the range of about 1: 1 to about 6: 1. The grafted monomers are used in a proportion of about 60 to 85 parts of methyl methacrylate, 15 to 30 parts of styrene and 0 to 15 parts of methylacrylate, methacrylate, ethylacrylate or acrylonitrile. The grafted polybutadiene is essentially uniformly distributed in the resin phase and is relatively non-agglomerated, ie, it essentially has no aggregates greater than about 1 mire.

The compositions can be produced by mixing the resinous terpolymer, which can be prepared through a reaction initiated with a free radical in the presence of a solvent and in a two-stage system whereby the monomer mixture is charged into a first reactor and it is polymerized at about 20 to 40% solids and then in a second reactor where the complete conversion is carried out; with the polybutadiene grafted in appropriate amounts. Alternatively, the compositions herein can be prepared through the inter-polymerization of all monomers, using a suitable emulsifier, in: the presence of polybutadiene gum, preferably in the latex form, under grafting conditions such as: it is explained later.

Any known process can be used to produce the resin phase. It is preferred, however, that the resin phase be produced by mixing the appropriate concentration of monomers in a solvent such as toluene of about 60 to 80% monomer concentration. A suitable initiator such as peroxide,! from Benzoyl, di-t-butyl peroxide and the like can be added in the presence of a molecular weight control additive such as an alkyl mercaptan, for example, n-dodecyl mercaptan, n-octyl mercaptan, t-dodecyl mercaptan, benzyl mercaptan and similar. As mentioned above, this polymerization is preferably conducted in a two-stage system whereby the monomer solution is charged into the reactor of the first stage and polymerized from about 80 ° C to 110 ° C for about 12 to 24 hours . The degree of conversion is preferably adjusted from about 1 to 3% solids per hour. The polymer of the first stage is then preferably transferred to a second stage such as a plug flow reactor where the complete conversion of the monomer to polymer is carried out. The final solids content is generally in the range of about 60 to 70%. The initiators can be used in amounts in the range of about 0.01 to 5.0% by weight, based on the weight of the monomers. The molecular weight control additive can be used in equal amounts, by weight, again based on the weight of the monomers.

Additives such as heat and light stabilizers, antioxidants, lubricants, plasticizers, pigments, fillers, colorants and the like can be added to the resin phase, after or during the formation. Others; - additives they include antioxidants, flow promoters, mold releasers, dyes, UV stabilizers and formulations imparting gamma stability, chemical resistance and / or static dissipative properties.

The grafted rubber phase is prepared through a sequential and controlled addition of process monomers that inhibit agglomeration and / or aggregation of the gummy particles. In the process in which it is essentially a standard free radical initiation polymerization, 1 wherein at least one monomer has the best compatibility as a polymer to that of the resin phase is added to rubber latex and any other monomer which also Grafting is being done on gum, conventional initiators, and other polymerization components are used.

Without wishing to be bound by any theory, it is believed that non-agglomeration is caused by the placement of; an essentially uniform shell of resin around rubbery particles where the outer layer of the shell is composed mainly of a controllably added monomer. ": Monomer that is added in a controlled manner should be added for a period of at least 15 minutes, preferably at least 1 hour, and more preferably around 1 to 3 hours, within the grafting reaction occurring during the addition and preferably | it [leaves continue later for approximately 1 hour. The initiator when it is in a redox type can be included in the reactor initially, it can be added simultaneously with the monomer controlled either in the same stream or in a separate stream; or ultraviolet light can be used. Generally, the initiator is used in an amount of up to about 4 times the standard amounts used in U.S. Patent No. 4,085,166. When the initiator is added at the same time that the controlled monomer either the oxidant or reduction portion can be placed in the reactor initially and only the other portion needs to be added in a controlled manner. The reaction is conducted in the pH range of about 6.0 to 8.5 and in the temperature range of from about room temperature to about 65 ° C although none of these have been found to be critical to the present invention.

Examples of suitable .redox initiator systems include: t-butyl hydroperoxide, eumeno hydroperoxide, hydrogen peroxide, potassium persulfate-iron sulfoxylate sodium formaldehyde; hydroperoxide tetraethylene pentamine or dihydroacetone; hydrophoxide-bisulfite systems; and other well-known systems.; j The resinous phase and the rubbery phases can be mixed together in any known manner such as through the use of a ball mill, hot rollers, mixed by emulsion or the like.

It is preferred that the mixing operation be carried out in a devolatilizer-extruder in a manner described in column 3, lines 3 to 72 of the aforementioned U.S. Patent No. 3,354,238, the section of which is incorporated by reference herein.

The acrylic polymers could be multipolymers. The compositions comprise a mixture of about 70 to about 90%, preferably about 75 to about 85% of a resinous terpolymer of about 65 to 75 parts of methylmethacrylate, methylmethacrylate, from about 18 to about 24 parts of styrene and about 2 to about about 12 parts of ethylacrylate and, correspondingly,; from about 5 to about 30%, preferably from about 10 to about 25%, of polybutadiene grafted with from about 17 to 22 parts of methyl methacrylate, from 4 to 7 parts of styrene and from O: to 3 parts of ethylacrylate.

The methyl methacrylate copolymer used in! the compositions will contain a predominant amount, for example from about 50 to about 90 parts by weight, preferably from 50 to 80 parts by weight, of methyl methacrylate and a minor amount, for example; from about 10 to about 50 parts by weight, preferably 20 to 40 parts by weight, of one or more ethylenically unsaturated monomers such as styrene, acrylonitrile, methyl acrylate, ethyl acrylate and mixtures thereof. Preferably, the ethylenically unsaturated monomer comprises a mixture of styrene and acrylonitrile or styrene and ethylacrylate wherein the styrene is present in the copolymer in an amount of about 10%. to about 40, preferably 15 to 30, parts by weight and the acrylonitrile is present in the copolymer in an amount of about 5 to about 30, preferably 5 to 20, parts by weight, based on. he. The weight of the copolymer or the ethyl acrylate is present in [the copolymer in an amount of from about 3 to about 10, preferably from 5 to 10 parts, by weight, based on the weight of the copolymer. Such copolymers: methyl methacrylate are well known in the prior art, for example, U.S. Patent Nos. 3,261,887; 3,354,238; 4,085,166; 4,228,256; 4,242,469; 5,061,747; and 5,290, 860. ' Preferably, the methyl methacrylate copolymer will have a weight average molecular weight of at least about 50,000, for example from about 100,000 to about 300,000 and a glass transition temperature I of at least 50 ° C. Typically",; The methyl methacrylate copolymer will have an index .: refraction from about 1.50 to about 1.53, preferably from 1.51 to 1.52, (as measured in accordance with ASTM D-542).

Preferably, the composition includes an impact modifier having a refractive index within about 0.005 units, preferably within 0.003 units, of the refractive index of the methyl methacrylate copolymer (as measured according to ASTM D-542). Typically, the impact modifier will be present in an amount from about 2: to about 30, preferably 5 to 20% by weight based on the weight of the copolymer plus the polyether ester amide plus the impact modifier.

Preferred impact modifiers for incorporation into the multipolymer compositions of. The present invention includes copolymers of "conjugated diene graft" rubber with one or more unsaturated ethylene-unsaturated monomers as well as acrylic copolymers having a core / shell structure.

In the case where the impact modifier comprises a conjugated diene rubber copolymer, the rubber is preferably polybutadiene which is present in an amount of about 50 to about 90, preferably 70 to 80 parts. by weight, based on the weight of the impact modifier, and the monomer (s) ethylenically unsaturated grafted to the rubber: polybutadiene typically present in an amount of about 10 to about 50, preferably 15 to 40 parts by weight, based on the weight of the impact modifier. Typically, the ethylenically unsaturated monomer to be grafted to the conjugated diene gum will be a C1-C alkyl acrylate such as methyl acrylate, ethyl acrylate, propyl acrylate or butyl acrylate; a C 1 -C 4 alkyl methacrylate such as methyl methacrylate, ethyl methacrylate, propyl methacrylate or butyl methacrylate; a styrene such as styrene or alpha-methylstyrene; a vinyl ether; a vinyl halide such as vinyl chloride; an ethyl such acrylonitrile or methacrylonitrile; an olefin or 'their mixtures. Preferably the ethylenically unsaturated monomer (s) to be grafted to the conjugated diene rubber comprises a mixture of methyl methacrylate and styrene monomer, with a proportion of methyl methacrylate: styrene being in the range of about 2: 1 to about 5: 1, preferably 2.5: 1 to 4.5: 1.

In the case where the modifying impact comprises an acrylic copolymer having a core / shell structure, it is preferred that the core / shell structure comprises a core of interlaced poly (alkylmethacrylate) or an entangled diene rubber and a shell of an copolymer of an alkyl acrylate (for example, methylacrylate) and styrene.

It is further preferred that the poly (alkyl methacrylate) comprises poly (methyl methacrylate), the diene rubber comprises polybutadiene rubber and an alkyl acrylate comprises butyl acrylate. It is especially preferred that there is an additional outer shell of poly (methyl methacrylate) in addition to the shell of the alkyl acrylate / styrene copolymer.

The acrylic polymers also include alloys based on commercially modified acrylic multipolymers, such as XT® and Cyrolite® multipolymers (Evonik Cyro LLC, Parsippany, NJ), where when mixed with polycarbonates they produce materials that have high impact strengths with Izod values. serrations superior to polycarbonate in sections with a thickness of 2.54 cm (1 inch). These alloys also offer a good balance of mechanical strength, heat resistance and processability that make them commercially attractive. The use of high :: flux versions of the above-specified modified acrylic multipolymers has resulted in Izod jagged: even larger in sections with a thickness of 0.32 cm (1/8 inch) whose results are superior to those of pure polycarbonates . These prior materials have outstanding processability and maintain a good balance of mechanical strength and heat resistance.;: |:: Alloys of acrylic multipolymers Modified commercial rubber and polycarbonate according to the invention may be in the range of a weight ratio of from about 20:80 to about 80:20. The proportion of rubber grafted to the polymer in the modified acrylic rubber multipolymers used in the invention is in the weight range of about 5:95 to about 25:75. The rubber, preferably, comprises about 14% of the alloy, of multipolymer. The multipolymer component of the alloy comprises from about 60 to about 80 parts by weight of methyl methacrylate, from about 15 to about 30 parts by weight of styrene, and up to about 15 parts by weight of methylacrylate, ethylacrylate, or acrylonitrile. The graft monomers in the modified rubber acrylics of the invention comprise the weight of from about 60 to about 85 parts of methyl methacrylate, from about 15 to about 30 parts of styrene, and up to about 15 parts of methylacrylate, ethylacrylate, or acrylonitrile. The weight ratio of the gum to the graft monomers in the graft rubber is in the range of about 1: 2 to about 6: 1.

The modified acrylic multipolymers of rubber used include an unsaturated gum, the polybutadiene being preferred. In practice, the multipolymers commercial rubber modified acrylics having a weight ratio of rubber to graft monomers of about 3: 1 can be used in the invention.

The modified acrylic rubber alloys sold under the trademarks XT® and Cyrolite® by Evonik Cyro LLC used in this invention are manufactured in accordance with one or more of the following U.S. Patent Nos; A. Nos. 3,261,887, 3,354,238, 4,085,166, 4,228,256, and 4,242,469 whose patents are incorporated herein by reference. ,,; The compositions of the modified rubber acrylic multipolymers are particularly determined in the U.S. Patent. A. No. 4,228,256, wherein the proportions of the components of the modified acrylic multipolymer gums given above can be found.

The multipolymer component of the commercially available alloys, XT® alloys is a terpolymer of about 60% to about 70%; MMA >; about 20% styrene, and about; 10%: to approximately 20% acrylonitrile. The multipolymer component of the commercially available Cyrolite® alloy is a terpolymer of about 5% '; of ethylacrylate, from about 15% to about 2% styrene, and 70% to about 80% of M Ar. These alloys all contain approximately 14% gpmaiily and their rubber graft and their multipolymer components' are substantially free of alpha-methylstyrene, (meth) acrylonitrile, maleic anhydride, and n-substituted maleimide.

The proportions and percentages above are all by weight.

Various polycarbonates can be used in the invention, such as Lexan® 181 polycarbonate available from General Electric Company (Stamford, CT), Caliber® 302-60 polycarbonate available from The Dow Chemical Company (Midland, MI), and Makrolon® 3103 available from Mobay Chemical Company (Pittsburgh, ??). These materials can be made in accordance with the Patents of US Pat. No. 4,885,335. and 4,883,836 which are incorporated herein by reference or in accordance with the prior art cited in those patents.

The additives with antimicrobial effect are selected from a group including silver-based antimicrophobic agents, including glass powders containing silver, silver zeolite products, silver-containing compounds of tetravalent metals, for example, antimicrobial glass compositions. of titanium, zirconium and tin, and nano-silver additives. The antimicrobial additive is present in an amount between 0.1 to: p-0%, preferably 0.2 to 5.0%, more preferably 0.3 to 2.5% by weight of the final composition. 1 - | The antimicrobial material can be used to produce a molded compound through an extrusion method. The antimicrobial compound is first dispersed through known methods in an acrylic carrier resin having a controlled moisture content. By weight, the resin contains no more than 1% moisture. Preferably, the moisture content is less than 0.4% and, more preferably, less than 0.1%. The resin can be made through any conventional polymerization method including, but not limited to, emulsion method, volume, solution, granulate and suspension. This resin can be fed into an extruder together with the main acrylic resin and then granulated to form the product of the molded compound. The extruder can be either a single screw extruder or a twin screw extruder. The screw speed of the extruder is not greater than 250 revolutions per minute (rpm). More preferably it is a screw speed of less than 150 rpm and more preferably is a screw speed of less than 120 rpm. The process window is limited to melting temperatures of 193.33 ° C to 243.33 ° C (380 ° F to 470 ° F). A more preferred melting temperature is .. between 198.89 ° C and 232.22 ° C (390 ° F and 450 ° F). More preferred is a melting temperature of between 204.45 ° C and 218.33 ° C (400 ° F and 425 ° F).

The antimicrobial material can also be used to produce molded parts through a method; by injection. Using the molded composite produced from the above antimicrobial material, the resin contains no more than 1% moisture by weight. Preferably, the moisture content is less than 0.4% and, more preferably, less than 0.1%. The resin can then be fed into an injection molding together with other optional additives. A suitable range of melting temperatures for molded compounds is from 193.33 ° C to 251.67 ° C (380 ° F 'to 485 ° F), more preferably 193.33 ° C to 243.33 ° C (380 ° F to 470 ° F) and more preferably 221.11 ° C to 243.33 ° C (430 ° F to 470 ° F).

The antimicrobial material can also be used to produce a sheet product through an extrusion method. The antimicrobial compound is first dispersed through known methods in an acrylic carrier resin having a controlled moisture content. By weight, the resin contains no more than 1% moisture. Preferably; the moisture content is less than 0.4% and, more preferably, less than 0.1%. The resin can be made through any conventional polymerization method including, but not limited to, method-emulsion, volume, solution, granulate and suspension. This resin can be fed into an extruder together with the main acrylic resin. He; The extruder can be either an individual screw extruder or a twin screw extruder. The speed of the spindle: the extruder is not greater than 250 revolutions per minute :: írpm).

More preferably it is a screw speed of less than 150 rpm and more preferably is a screw speed of less than 120 rpm. This combination is then forced through a die of sheet and through a calendering roller system to form a sheet product. The process window is limited in terms of polymer viscosity and melting temperature, more preferably to compositions of 1.0 to 3.0 g / 10 minutes of melt flow rate (load 230 ° C @ 3.8 kg) and melting temperatures of 193.33 ° C at 243.33 ° C (380 ° F to 470 ° F). A melting temperature is between 193.33 ° C to 232.22 ° C (380 ° F and 450 ° F). More preferred is a melting temperature between 193.33 ° C and 218.33 ° C (380 ° F and 425 ° F).

The antimicrobial material can also be used to produce a film product through an extrusion or film calendering method. The antimicrobial compound is first dispersed through known methods in an acrylic carrier resin that has! a controlled moisture content. By weight, the resin: contains no more than 1% moisture. Preferably, the moisture content is less than 0.4% and, more preferably, less than 0.1%. The resin can be made through any conventional polymerization method including, but not limited to, emulsion method, volume, solution, granulate and suspension. This resin can then be fed in an extruder together with the main acrylic resin. The extruder can be either a single screw extruder or a twin screw extruder. The screw speed of the extruder is not greater than 250 revolutions per minute (rpm). More preferably it is a lower spindle speed of 150 rpm and more preferably is a spindle speed less than 120 rpm. This combination is then forced through a sheet die and through a calendering roller system to form the film product. The film extruder is in the range of 0.01 to 0.5, mm, more preferably between 0.02 and 0.08 mm. ! The antimicrobial compositions can also be used to produce a sheet product. The antimicrobial compile is first dispersed in a resin-carrier silica. This resin can then be dissolved in either a MMA monomer or a pre-polymerized MMA syrup. This syrup is then poured into the cells to cure through; of well-known cell molding methods. Largely; In the same process, the material can also be used-to produce a sheet product from a continuous molding method where the syrup is poured and cured. "Two steel belts fused in motion. The mold can be carried out at temperatures in the range of 226.67 ° C-500 ° C (440 ° -500 ° F), preferably 226. 70C-246.11 ° C (440 ° to 475 ° F) and more preferably 226. FTC- 237. 78 ° C (440 ° to 460 ° F).

The antimicrobial compositions can also be used to produce many other products in addition to the molded compound, the molded parts, the sheets and films can be formed through the processes described above. For example, extruded profiles, thermoformed and manufactured articles and foam products.

The following examples are set forth for purposes of illustration only and are not construed as limitations of the present invention except as determined in the appended claims. All parts and percentages are by weight unless otherwise indicated. All parts and percentages are by weight and temperatures in degrees Celsius unless explicitly stated otherwise.

Examples The products are characterized using standard assay processes, as follows: -; Typically certified properties for medical degrees of the CYROLITE® family from Evonik Cyro LLC;; ::: Degrees of liberation of silver ions, by means of a modified process: The availability of silver and grades: of liberation of silver ions were measured by extraction of molded chips by injection in purified water. It was extracted a single chip (dimensions 5.8x7.6x0.32 cm (2"x3" xl / 8")) in 100 ml per 24 hours.The amount of silver in the extract solution was recorded by inductively coupled plate spectrometry; Biological, following the JIS Z 2801 test for antimicrobial activity of plastics, now also ISO 22196.

The following abbreviations were used in the following Tables: Humidity% = percentage by weight of H20 in a sample, medica by Karl Fischer titration; % T = light transmission; % of visible light (400 nm - 700 nm) through, a sample with a thickness of 3 mm; Yl = Yellowish index, measured by ASTM D-1003; % H = percentage of mist, measured by ASTM D-1003; (Use of a mist measurement or spectrophotometer).

L * = coordinate L * of the CIELAB Color Scale Color; b * = coordinate b * of the CIELAB Color Scale; i R = degree of silver release in 24 hours: in nanograms / cm2. Indicates the quantity of biologically effective silver in the final product. It is an indication;; j of antimicrobial performance;; Fusion Flow = Degree of flow of fuel in grams / 10 minutes at 230 ° C and 5.0 kg load, except when otherwise indicated; '' Ref = In reflectance ?.? = Not Applicable NT. = Not Tested opq = opaque S.a. = Staphylococcus aureus; P. a. = Pseudomonas aeruginosa; S.c. = Salmonella choleraesius ATCC = American Type Culture Collection Both conditions of the composition and the process were found to affect the performance of the product. Five critical parameters were identified: level of additive loading, presence of selected compounds, melting temperature, spindle speed, and moisture content of the resins fed, or alternatively, the; final product in composite. The effects are manifested in the appearance of the product (discoloration) and antimicrobial activity, or alternatively, degrees of liberation of silver ions. The underlying changes have not been clearly identified. It is speculated that the combination; The extruder heat, shear force, moisture and certain compounds result in rapid activation of the silver during the formation of the compounds "which prematurely consumes the silver biologically: effective available in the final product." The effects of these parameters they are illustrated in the following examples. All the grades used were acrylic-based polymer Evonik Cyro LLC or multi-polymeric compounds.

To evaluate the type of base resin, it was formed! in compound an antimicrobial additive in various acrylic resins, in natural, transparent and opaque colors. Some representative examples are as follows: Table 1 All trademarks are registered trademarks of Evonik Cyro LLC, Parsippany, NJ, USA Example 1 Table 2 illustrates the antimicrobial activity of some of the above base resins with 1.5% by weight of a silver-based antimicrobial glass powder. In all the examples, the antimicrobial activity was measured by JIS Z 2801 and calculated as: [log (B / A) - log (C / A)] = [log (B / C)] where: A = average number of viable cells of bacteria immediately after inoculation in a treated test piece; .

B = average number of viable cells of bacteria in an untreated test piece after 24 hours; Y [ C = average number of viable bacteria cells in the antimicrobial test piece after 24 hours.

Table 2 Example 2 Table 3 illustrates the effect of the loading of the antimicrobial additive. The filler is expressed as the active ingredient in% by weight per total weight of the composition. All samples used a silver-based antimicrobial glass powder in CRYOLITE® G20-HiFlo.

Table 3 * = Different sample group for the JIS Z 2801 test only. Inoculation at 0, 24 hours, 48 hours and 72 hours. Viable count reading after 96 hours.

As seen, the properties depend on the load of antimicrobial additive. The optics and the degrees of liberation of silver ions were measured in chips Injection molded 0.32 cm (1/8") thick chips into 5.08x7.63 cm (2" x3") thickness.The degrees of silver ion release and antimicrobial activity are in good correlation with the load of additive Most of the compositions showed a strong antimicrobial effect, with a degree of termination in excess of 6. orders of magnitude (R> 6.0) for both organisms tested Figure 1 illustrates the effect of additive loading in the degree of silver release, sufficient silver must be present so that the degree of release during compound formation does not reduce the silver content below that required to pass a specified efficacy test (either JIS Z 2801 or as specified by a customer.) However, excess silver is not desired as it raises the cost of the product.

Example 3 Table 4 illustrates the effect of moisture. All samples had 2.5% charge.

Table 4 Control = Resin without dilution 0% pure ion As seen, the moisture content during extrusion can significantly affect the properties of the product. Losses of up to 17% of the silver release grades have been recorded, depending on the moisture content and temperatures of the melting group.

Example 4 Table 5 illustrates the effect of barrel temperature, spindle speed and melting temperature during compound formation. All samples at 2.5% IonPure in CRYOLITE® G20-HiFlo.

Table 5 Note: 1 ° = a-17.22 ° C 1 lb-ft = 0.138 kg-m 1 psi = 0.0703 kg / cm2 As can be seen, the temperature of the barrel and the speed of the spindle during the fusion combination affect the optical properties and the degree of silver release of the product. Figure 2 illustrates the effects of ^ barrel temperature and spindle speed on 'the degree of release. It is desirable to maximize the available silver by increasing the silver available in the extruded product. This can be achieved by minimizing the degree of silver release during the combination. This is done by combining the lowest spindle speed and the lowest barrel temperature within the process parameters for a specific polymer. If either the spindle speed or the barrel temperature is too high, the viscosity of the melt becomes too high, for processing | Example 5 Table 6 reports the effect of the resin; ba¾é > the level of antimicrobial load and humidity. All-; the samples with the silver-based antimicrobial glass powder are summarized in Table 1.

Antimicrobial activity according to JIS Z-2801 for 24 hours. '" Table 6 * = 3.8 kg load, ",; 1 psi = 0.0703 kg / cm2; Z; Example 6 The antimicrobial compositions were also studied in injection molding under different process conditions, as illustrated in Table 7 and Figure 3. A significant effect was evident; from; the molding temperature, with a specific discoloration of the material. The findings are important to guide, to ...; processors in the design of their process conditions.

Table 7 Note: 1 ° F = to -17.22 ° C Example 7 Although the antimicrobial activities have an effect on the optical properties and the impact resistance of the feed base resins, the balance of the properties did not change significantly.

The illustrative properties listed in < Table 8 that mentions typical values of selected properties, the comparison between CYROLITE® G20 HIFLO and its composition with 2. 5% silver-based antimicrobial glass powder as an additive Table 8 Notes: 1 ° F = -17.22 ° C 1 ft-lb / in = 0.138 kg-m / 2.54 cm 1 in-inch / ° F = 2.54 cm - 2.54 cm / 17.22 ° C 1 psi = 0.0703 kg / cm2 1 ksi = 1 psi = 0.0703 kg / cm2 Although the invention has been described above with reference to its specific embodiments, it is clear that many changes and modifications can be made without departing from the inventive concept described herein. Accordingly, it is intended to cover all these changes, modifications and variations that fall within the spirit and scope of the appended claims. All applications for patents, patents and other publications cited herein are incorporated by reference in their entirety.

It is noted that in relation to this date, the best method known to the applicant to carry; the practice of said invention is that which is clear from the present description of the invention.

Claims (33)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. - A method for producing an acrylic material having a desired transparency and antimicrobial efficacy, characterized in that it comprises the steps of: combining a polymer selected from the group consists of acrylic-based polymers, acrylic multipolymers, polymers based on modified acrylic; of impact, mixtures of acrylic-based polymers and their mixtures with an antimicrobial additive and, optionally, other additives to form a fusion group: mixing the merger of the melting group wherein, one or more of the melting mixing equipment, the spindle configuration, the residence time, the spindle speed and the melting temperature of the moisture content of the melting group is maintained within from a predetermined interval; Y solidify the mixed melting group of the mixture to form the acrylic material with the desired transparency and antimicrobial efficacy.

2. - The method of compliance with "|; ' claim 1, characterized in that the step of imezciado The fusion uses an extruder at a screw speed that does not exceed 250 rpm.

3. - The method according to claim 2, characterized in that the spindle speed is less than 150 rpm.

4. - The method according to claim 2, characterized in that the step of mixing the melt is at a temperature in the range of 198.89 ° C to 243.33 ° C (390 ° F to 470 ° F). |

5. - The method according to claim 4, characterized in that the step of the melting mixture is at a temperature in the range of 204.45 ° C and 218.33 ° C (400 ° F to 425 ° F). :

6. - The method according to claim 4, characterized in that the melting mixing step uses the polymer having a controlled moisture content not exceeding 1% by weight. '

7. - The method of compliance with ...; Claim 6, characterized in that the content! of moisture is less than 0.1% by weight. [

8. - The method according to claim 2, characterized in that the resin components including the polymer are formed through; polymerization through a method selected from the "group consisting of emulsion, volume, solution, granulation and suspension.

9. - The method according to claim 2, characterized in that the antimicrobial additive is selected from the group consisting of silver-based antimicrobial agents, including silver zeolite products, silver-containing compounds of tetravalent metals, such as titanium, zirconium and tin , antimicrobial glass compositions, and nano-silver additives.

10. - The method according to: claim 9, characterized in that the antimicrobial additive is added in an amount of 0.1% to 10%, by weight of the final composition.

11. - The method according to claim 9, characterized in that the antimicrobial additive is added in an amount of 0.3% to 2.5%, by weight of the final composition.

12. - The method according to claim 10, characterized in that the resin components are also combined with an additive which. imparts impact resistance j

13. - The method according to claim 12, characterized in that the additive 'that imparts impact resistance is selected from the group consisting of polymers with a low Tg and copolymer O'S of aliphatic esters of acrylic acid, polymers and copolymers of 1,3-butadiene, styrene / butadiene, styrene / isoprene and styrene / ethylene-butylene copolymers, EPDM gums, polyisobutylene, polyurethane and silicone gums.

14. The method according to claim 10, characterized in that the resin components are further combined with one or more effective auxiliary additives to promote anti-oxidation, flow, mold release, color, instability, gamma stability, chemical resistance or static dissipative properties.

15. The method according to claim 10, characterized in that the acrylic material is formed: in antimicrobial products selected from the group "consisting of medical devices and accessories, including control valves, luer connectors, filter housings, nails, sites- And, measuring cups, etc., and consumer applications such as vacuum inhibitors, dispensers; of paper towels, manual dryers, tubs, showers, and floors for bathrooms and kitchens.

16. - The method according to: claim 11, characterized in that the group of; The mixed fusion fusion is granulated into granules.

17. - The method according to claim 16, characterized in that the gráhulqsj is they inject in injected parts.

18. - The method according to claim 17, characterized in that the temperature of the injection material is in the range of 193.33 ° C to 251.67 ° C (380 ° F to 485 ° F).

19. - The method according to claim 18, characterized in that the injection molding step is at a temperature in the range of 221.11 ° C to 243.33 ° C (430 ° F to 470 ° F)

20. - The method according to claim 16, characterized in that the granules! They are extruded into an extruded sheet, film, extruded profiles, or foam products.;

21. - The method according to claim 16, characterized in that the granules are formed in thermoformed articles. | · |. :

22. - A method for producing an acrylic molded compound having the desired transparency and antimicrobial efficacy, characterized in that it comprises the steps' of: combine acrylic multipolymers with a. antimicrobial additive and, optionally, with other additives, to form a fusion group; :: °: 'mix the fusion of the fusion group where! one or more of the fusion mixing equipment, configuration, spindle operation, residence time, spindle speed, melting temperature and moisture content of such a melting group is maintained within a predetermined range: and forcing the combination through an extruder die and a granulator to form the product of the molded compound with the desired transparency and the antimicrobial application.

23. - The method according to claim 22, characterized in that the melting mixing step uses an extruder at a screw speed exceeding 250 rpm.

24. - The method according to claim 23, characterized in that the spindle speed1 is less than 150 rpm. :

25. - The method according to claim 22, characterized in that the step of mixing the melt at a temperature in the range of 193.33 ° C to 243.33 ° C (380 ° F to 470 ° F). ";

26. - The method according to claim 25, characterized in that the step of mixing the melt is at a temperature in the range of 204.45 ° C and 218.33 ° C (400 ° F to 425 ° F).

27. - The method according to claim 25, characterized in that the mixing step of the melt uses the polymer having a controlled moisture content not exceeding 1% by weight.

28. - The method according to claim 27, characterized in that the content. of moisture is less than 0.1% by weight.

29. - The method according to claim 27, characterized in that the antimicrobial additive is selected from the group consisting of antimicrobial agents based on silver, including silver zeolite products, silver-containing compounds of tetravalent metals, such as titanium, zirconium and tin, antimicrobial glass compositions and nano-silver additives.

30. - The method according to claim 29, characterized in that the antimicrobial additive is added in an amount of 0.1% to 10%; by weight, of the final composition.

31. - The method of compliance with - -i claim 29, characterized in that the antimicrobial additive is added in an amount of 0.3% to 2.5%, by weight, of the final composition.; · | ':

32. - The method of compliance with; claim 22, characterized in that the acrylic material1 is formed into selected antimicrobial products: from the group consisting of devices and accessories: medical, including checker valves, connectors': ¾uer, filter housings, nails, Y-sites, cups 'measurement, etc., and consumer applications such as vacuum inhibitors, paper towel dispensers, manual dryers, tubs, showers, and floors for bathrooms and kitchens.

33. - The method of compliance with; Claim 22, characterized in that the melting temperature and the temperature of the barrel are both selected to a minimum which maintains a combination of viscosity suitable for the given extruder.